Day 1 :
Keynote Forum
Peter Winkler
University of Nevada, USA
Keynote: Siegert’s curse and redemption: Taming and domesticating divergent wave functions
Time : 09:00-09:40
Biography:
Peter Winkler has obtained his Dr. rer.nat. degree (PhD) in Nuclear Physics and later his Dr. rer. nat. habil. degree from the University Erlangen in Germany. In 1979, he joined the Physics Department of the University of Nevada at Reno for teaching and research. His research interests focused on atomic many-body theory. He obtained tenure in 1985 and became Emeritus Professor in 2013 after having directed 12 students in their dissertation research. He is a Fellow of the American Physical Society.
Abstract:
Metastable states of quantum systems can be evaluated as complex-valued eigen solutions of the time-independent Schrődinger equation if complex boundary conditions are applied. Such resonance boundary conditions have been formulated in the early days of quantum mechanics but, initially few calculations have been performed utilizing this concept because the corresponding wave functions diverge asymptotically. Subsequent advances in the computation of energies and widths of metastable states will be discussed when Siegert boundary conditions are applied to achieve the necessary analytic continuation onto the complex energy plane as well as schemes to sidestep the divergences altogether. Examples including potential resonances and multiply excited electronic states of atoms and ions illustrate the wide applicability of this approach.
Keynote Forum
Xueqiao Xu
Lawrence Livermore National Laboratory, USA
Keynote: Modeling tokamak boundary plasma turbulence and its role in setting divertor heat flux widths
Time : 09:40-10:20
Biography:
Xueqiao Xu has his expertise in Plasma Physics and Controlled Nuclear Fusion. He has completed his PhD in 1990 from the University of Texas at Austin. He is a Principal Physicist at Lawrence Livermore National Laboratory and Guest Professor of Peking University.
Abstract:
The success of fusion experiments in ITER (International Thermonuclear Experimental Reactor) will require demonstrated
reliability in the plasma facing components (PFCs) to sustain the required pulse lengths. Understanding the physics of the scrape-off layer (SOL) width outside the magnetic separatrix is a crucial problem that must be solved in order to design a successful fusion reactor, as pointed out by the 2015 US Fusion Energy Sciences community workshops on Plasma-Material Interaction (PMI) and transients. The dominant view is that the Goldston “heuristic drift” model determines the peak heat flux. This model relies on magnetic drifts for ions and anomalous transport for electrons, but the anomalous transport mechanisms are not well understood and may depend on which edge transport regime the tokamak is operated in. In this work, massively parallel BOUT++ simulations are used to investigate the nature of SOL transport in multiple international tokamaks, such as C-Mod, DIII-D and EAST. Nonlinear simulations find saturated modes localized at the outer mid-plane that are similar to the quasi-coherent modes; characteristics such as frequency, wavenumber, phase and fluctuation amplitudes are compared with probe and Phase Contrast Imaging measurements on the C-Mod enhanced D H-mode discharges. The heat flux transported to divert or displays a width that is within a factor of 2 of the profile measured by IR camera and probe measurements. The parallel electron heat fluxes onto the target from the BOUT++ simulations of C-Mod, DIII-D and EAST follow the experimental heat flux width scaling of the inverse dependence on the poloidal magnetic field with an outlier. This shows that blob-like turbulence is likely to play an important role in present devices, particularly for electrons. Further turbulence statistics analysis shows that the blobs are generated near the pedestal peak gradient region inside the magnetic separatrix and contribute to the transport of the particle and heat in the SOL region.
Keynote Forum
Xiaodong Li
National University of Defense Technology, China
Keynote: What does an atomic nucleus look like?
Time : 10:20-11:00
Biography:
Xiaodong Li is a PhD holder from Université de Montréal (1993, crystal structure of mesophase molecules); MS from Nankai University (1981, functional polymers), BS from Tianjin University (1977). He is a Senior Professor in NUDT (National University of Defense Technology) researching and teaching in the fields of Polymer Chemistry and Physics, Material Chemistry, Ceramic Fibers And Composites, Material Engineering, Environmental Chemistry, Crystal Chemistry, Structure Chemistry and Nuclear Chemistry and Structure.
Abstract:
The more and more knowledge about molecular structure builds the footstone of modern chemistry. That arouses curiosity about the structure of the inner core of atoms. However, the nucleus is too small and is embedded by very thick electron “cloud” in normal state. What does a nucleus look like? Is it possible to “guess” it in a way as molecules? A new nuclear model of “ring plus extra nucleon” is proposed. The proton (P) and neutron (N) bind alternatively to form a right-angle folding ring. Based on it, extra nucleon binds in a similar way. Hereby, the shapes of some light nuclides were figured out, which are mostly not spheres, but with a generally linear relationship between the size and mass. The most excitement of this model is that, in even Z rings, the gravity centers of P and N are superimposed, while in odd Z rings, they must be eccentric. The eccentricity leads a lower EB/A. The extra nucleon(s) shift the eccentricity and the binding energy. This is exactly consistent with the normal even/odd zigzag feature found in EB/A and other properties in various cases. The model is also supported
by many basic evidence, including the nuclear stability and isotope limitation (see the attached figure), the spin similarity of “mirror” nuclides, the neutron halo of extremely neutron-rich nuclides and so on. From the nuclear structure, one may also explain the decay modes of unstable nuclide and furthermore, find some structural correlation with decayed daughter isotope. Since a huge task of computation is necessary to build the structure of large nuclide, where many “isomers” will be possible, a technique such as “nuclear mechanics”, which considers the weak interaction between all non-binding nucleons, is needed. It will be interesting that the combination of this model with quantum theory to obtain some new and more quantitative results. A correct nuclear structure may be useful to establish a more reasonable potential function in quantum computation.